Embedded Electronics

Used for:
  • Embedded Intelligence
  • Self-Monitoring Panels
  • Rapid Integration
  • Elimination of external wiring harnesses
Encapsulated USB Devices
  • Internal Linux Processors
  • Connectors Distributed around Panels
Sensors
  • Strain Gauges, Accelerometers, etc.

The embedding of small electronic devices, such as strain gauges, accelerometers, temperature sensors, vibration sensors, and magnetic sensors controlled by USB connections, is being explored to understand the feasibility of manufacturing smart panels.

We have demonstrated the ability to use Ultrasonic Consolidation (UC) to embed USB-based thermal sensors into aluminum, and are working toward embedding suites of sensors, heaters, and other devices connected by USB hubs, which can be independently monitored and controlled using embedded Linux processors. We have shown that electronics can be embedded at room temperature, but with some inter-layer delamination between the ultrasonically bonded aluminum layers. Embedding sensors and electronics at 300oF to overcome the delamination issues resulted in optimal bonding, and the sensors used thus far have functioned normally. Thus, sensors, electronics, and wiring which can withstand 300oF temperatures for periods of a few hours to a few days without failure are candidates for embedded systems. In the future, we will investigate other UC parameter combinations to ascertain the quality of embedding at lower temperatures.

Embedding Process

Step 1: Build Substrate
A substrate panel is created using UC commensurate with the desired end application geometry. This substrate must have a sufficient thickness to accommodate the dimensions of the sensor/electronic being embedded.

  

Step 2: Mill Pocket
A pocket to embed the sensor is milled into the substrate using a CNC mill attached to the UC machine.

  

Step 3: Place, Bond and Pot Sensor
The sensor is placed within the pocket and secured in place using a thermally conductive/electrically nonconductive epoxy. The pocket is then potted (filled) with an epoxy to provide a solid substrate for subsequent UC operations. Once hardened, the face is milled to prepare for the next layer.

  

Step 4: Continue Build
UC aluminum tape is then ultrasonically welded to the substrate to embed the electronic sensor. (1, 4, & 8 layers of subsequently bonded aluminum are shown.)

Step 5: Calibrate and Test
In this example, two embedded thermal sensors are tested to ensure functionality post-embedding. Using the linear characteristics of the given sensors, they are calibrated using the average value obtained from the sensor at a given temperature. Several data points are obtained and plotted to obtain the linear equation associated with each sensor. Heating the substrate in which each sensor is embedded shows the resulting temperature increase of the sensors in degrees Fahrenheit. The sensors are now ready to be used and tested within a given environment.